Formal (Left) vs. Casual (Right)
Have you ever eaten a whole cake by mistake? Or finished your homework completely? In Japanese, we use the grammar form 〜てしまいました (~te shimaimashita) for these situations.
Let’s learn the difference between the formal form and the casual version 〜ちゃいました (~chaimashita)!
🗣 Conversation: Oops!
Joy is talking to Ken about her diet failure.
(Ah… I ate the whole cake [by mistake].)
(Eh? Aren’t you on a diet?)
(Yes… I completely forgot [regret].)
💡 Meaning: Regret vs. Completion
This grammar pattern has two main meanings.
1. Regret / “Oops!” (失敗・後悔)
Use this when you did something you didn’t mean to do.
- 電車（でんしゃ）で ねてしまいました。
(I fell asleep on the train [oops!].) - サイフを おとしてしまいました。
(I dropped my wallet [oh no!].)
2. Completion / “All done!” (完了)
Use this when you finished something completely.
- 宿題（しゅくだい）は もう やってしまいました。
(I have already finished my homework completely.) - この本（ほん）を 読んでしまいました。
(I finished reading this book.)
📊 The Difference: Formal vs. Casual
〜てしまいました (~te shimaimashita) is the standard polite form.
In casual conversation, it changes to 〜ちゃいました (~chaimashita).
🚧 Joy’s Mistake (Common Error)
Don’t use “Chaimashita” when apologizing to your boss! It sounds too light.
❌ Wrong (To Boss):
すみません、寝坊（ねぼう）しちゃいました。
(Sorry, I overslept~ [sounds casual])
✅ Right (To Boss):
申し訳ありません、寝坊してしまいました。
(I am very sorry, I overslept [shows deep regret].)
🔥 Practice Quiz
Tap the box to check the answer!
Try using “Chaimashita” with your friends next time!
